Azerbaijan held a day of mourning on Thursday for the dozens of victims of an airliner crash in Kazakhstan, as questions were being asked over the cause of the disaster.

Azerbaijan on Thursday observed a nationwide day of mourning for the victims of the plane crash that killed 38 people and left all 29 survivors injured as speculation mounted about a possible cause of the disaster, with some experts saying that the airliner was damaged by Russian air defense fire.

National flags were lowered across Azerbaijan, traffic across the country stopped at noon, and signals were sounded from ships and trains as the country observed a nationwide moment of silence.